If its in an OnSetText script, easiest way is to just do something like this using the Font Tags feature.
(Where you have a font named RedFont in your project)
text = "{RedFont}" + text
If its in an OnOnline script or elsewhere it would be done a bit differently using the "TextWithTags" property.
The text object does have a .CurrentFont property (consult the SDK helpfile for all the properties of a textobject). The CurrentFont property only affects text added to the text object after you set the CurrentFont (since remember a textobject can have many different characters all with different fonts held within it).
#XPression